The present invention relates, in general, to a process for manufacturing a piston/cylinder assembly and, in particular, to the manufacture of a master cylinder for hydraulic brake units for automotive vehicles using pressure die casting starting material, squeeze die casting starting material or other fluid, semifluid, semisolid or pasty starting material, especially semisolid metal starting material (SSM material).
The present invention is concerned with a manufacturing technique which optimizes the fabrication of master cylinders. U.S. Pat. No. 4,565,066, granted on Jan. 21, 1986, corresponds to published German Patent Application No. 3 224 168 and discloses a pressure die casting mold for a master brake cylinder housing. This master brake cylinder housing has an axial master cylinder piston bore and a compensating bore. The axis of the compensating bore extends parallel to the axis of the master cylinder piston bore. The compensating bore extends between a compensating reservoir port which is disposed transverse to the longitudinal axis of the housing and a sealing chamber which is an extension of the master cylinder piston bore.
In U.S. Pat. No. 4,565,066, the casting mold has a core for the compensating bore. The longitudinal sections of this core, containing the longitudinal axis of the core, have a conical configuration with the narrowest point being adjacent to the compensating reservoir port and the cross-sections extending perpendicular to the longitudinal axis having a substantially kidney-shaped configuration with the concave side of the cross-sections facing the master cylinder piston bore.